Typical radar apparatuses detect a target object based on an echo signal and display an image of the echo on a display module (see JP2007-333482A). More specifically, the conventional target object detection is carried out as follows, for example.
The radar apparatus examines a level of the echo signals sequentially along a distance direction going from a location close to own ship toward a distant location from own ship, and stores information on continuous locations determined as having an echo level representative of a target object. The same processing is repeatedly carried out for all azimuth directions sequentially, and a similar continuity of the echo signals is also determined in the azimuth direction. When the continuity in the azimuth direction breaks off, this location is determined as a location of the target object.
However, for target objects such as a target ship located inside a bay, if it is surrounded by other target objects (land, bridges, etc.), the continuity of the echo signals may break off in the distance direction, and the above conventional target object detection cannot suitably detect the target objects.